The present invention relates to an optical amplifier and wavelength division multiplex light communication system.
FIG. 9 illustrates a wavelength division multiplex light communication system according to the prior art while FIG. 10 is a graph schematically showing the relationship between the number of channels in an optical amplifier used in the wavelength division multiplex light communication system of the prior art and the total light output power.
As shown in FIG. 9, the wavelength division multiplex light communication system of the prior art comprises a plurality (eight in this figure) of light transmitters 1 for transmitting light signals, a multiplexer 2 for wavelength division multiplexing a plurality of channel light signals transmitted from the light transmitters 1, a plurality of optical amplifiers 3 connected in series with one another for amplifying and translating the multiplex light signals wave division multiplexed by the multiplexer 2, a splitter 4 for wavelength separating the amplified light signals from the optical amplifiers 3 for each channel and a plurality of light receivers 5 each for receiving each light signal wavelength separated by the splitter 4.
In general, the optical amplifier used in the wavelength division multiplex light communication system is adapted to increase or decrease the total light output power depending on the number of channels.
The present invention provides an optical amplifier characterized by that the control is performed such that the total light output power Pt becomes equal to the maximum total light output power Pmax when the number of channels (n) is maximum (nmax) and also such that the total light output power Pt obtained by amplifying multiplex light signals substantially becomes
xe2x80x83Pt greater than Pmaxxc3x97n/nmax
when the number of light signal channels n is smaller than nmax.